Addition of Broad Bean Hull to Wheat Flour for the Development of High-Fiber Bread: Effects on Physical and Nutritional Properties.

Qianqian Ni,Helen E Hayes,Viren Ranawana,David Stead,Nicholas J Hayward,Vassilios Raikos

doi:10.3390/foods9091192

Abstract

The seed coat (hull) of broad bean (Vicia faba) (BBH) is a significant secondary product of processing with a promising nutritional profile. Bean hull has a high fiber content (49%), yet it remains underexploited as an ingredient by the food industry. This study investigated the potential of this secondary product to partially replace wheat flour for the development of high-fiber breads. Bread formulations with a range of supplementation levels (0%, 11%, 21% and 31%) were developed and tested for their nutritional and physical properties. The proximate composition of breads revealed that at 31% replacement, the fiber content was 19.19 g/100 g bread, which was significantly higher (p < 0.05) than control breads (3.62 g/100 g bread). The physical (specific volume, density and color) and textural properties of breads were affected by the addition of bean hull. Specific volume and hardness of breads were significantly reduced at ≥21% replacement compared to the control, which may reduce acceptability of the product by some consumer groups. Enzyme-linked immunosorbent assay (ELISA) showed that the gluten content of breads was significantly reduced with bean hull addition (62% depletion for 31% replacement). At 11%, 21% and 31% replacement, one portion (80 g of bread) contains 6.8 g, 11.6 g and 15.3 g of dietary fiber, respectively, which contributes 23%, 38% and 51% of the recommended daily fiber intake (30 g/day). In conclusion, bean hull can be a valuable source of dietary fiber in bread formulations. The study showed BBH could be used to replace up to 21% of the wheat flour without significantly impacting on bread texture and volume.

Highlights

Bread is an important staple food worldwide, which is typically made from wheat (Triticum aestivum) flour, salt, sugar, water, fat and baker’s yeast
When the fortification level was higher than 11%, the crumb surface was darker and presented smaller porous structure compared with the control bread
Since the temperature during baking is not above 100 ◦ C inside the bread [28], the crumb color is determined by the colors of ingredients used to make the recipe [25]. These results indicate that incorporation of broad bean hull (BBH) into bread has darkening effects in the inner part of bread, which is attributed to the color effects imparted by the ingredients

Summary

Introduction

Bread is an important staple food worldwide, which is typically made from wheat (Triticum aestivum) flour, salt, sugar, water, fat and baker’s yeast. Wheat flour is a key ingredient in bread making due to its unique endosperm protein composition (gliadins and glutenins). The latter are responsible for the formation of “gluten”, which is the term commonly used to describe the viscoelastic network of the dough that allows the entrapment of CO2 and contributes to the desired bread texture and volume [1]. The refinement process diminishes nutritional quality, in its fiber, vitamin and phytochemical contents [3]. To compensate for these nutritional losses, a multi-grain approach is often adopted by the baking industry.

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